Antisense oligonucleotides have received considerable theoretical consideration as potentially useful pharmacologic agents in human disease. R. Wagner, Nature 372, 333-335 (1994). However, practical applications of these molecules in actual models of human disease have been elusive. One important consideration in the pharmacologic application of these molecules is route of administration. Most experiments utilizing antisense oligonucleotides in vivo have involved direct application to limited regions of the brain (see C. Wahlestedt, Trends in Pharmacological Sciences 15, 42-46 (1994); J. Lai et al., Neuroreport 5, 1049-1052 (1994); K. Standifer et al., Neuron 12, 805-810 (1994); A. Akabayashi et al., Brain Research 21, 55-61 (1994)), or to spinal fluid (see e.g. L. Tseng et al., European J. Pharmacol. 258, R1-3 (1994); R. Raffa et al., European J. Pharmacol. 258, R5-7 (1994); F. Gillardon et al., European J. Neurosci. 6, 880-884 (1994)). Such applications have limited clinical utility due to their invasive nature.
The systemic administration of antisense oligonucleotides also poses significant problems with respect to pharmacologic application, not the least of which is the difficulty in targeting disease-involved tissues. In contrast, the lung is an excellent potential target for antisense oligonucleotide application since it may be approached noninvasively and in a tissue-specific manner. However, the technology involved in delivering antisense agents to the lung remains relatively undeveloped, and potential problems related to the application of antisense agents to the lung remain unexplored.
Adenosine may constitute an important mediator of bronchial asthma. R. Pauwels et al., Clinical & Exp. Allergy 21 Suppl. 1, 48-55 (1991); S. Holgate et al., Annals of the New York Acad. Sci. 629, 227-236 (1991). The potential role of adenosine in human asthma is supported by the experimental finding that, in contrast to normal individuals, asthmatic individuals respond to aerosolized adenosine with marked bronchoconstriction. M. Church and S. Holgate, Trends Pharmacol. Sci. 7, 49-50 (1986); M. Cushley et al., Br. J. Clin. Pharmacol. 15, 161-165 (1983). Similarly, asthmatic rabbits produced using the dust mite allergic rabbit model of human asthma also were shown to respond to aerosolized adenosine with marked bronchoconstriction, while non asthmatic rabbits showed no response. S. Ali et al., Agents Actions 37, 165-176 (1992). Recent work using this model system has suggested that adenosine-induced bronchoconstriction and bronchial hyperresponsiveness in asthma are mediated primarily through the stimulation of adenosine receptors. S. Ali et al., J. Pharmacol. Exp. Ther. 268, 1328-1334 (1994); S. Ali et al., Am. J. Physiol 266, L271-277 (1994).
Adenosine has also been shown to cause adverse effects, including death, when administered therapeutically for other diseases and conditions in subjects with previously undiagnosed hyperreactive airways. See e.g., R. P. Cowell et al., Brit. Heart J. 71(6),569-71 (1994); D. J. Pennell et al., Europ. J. Nuclear Med. 21(2), 170-2 (1994); R. Reed et al., Am. J. Emerg. Med. 21(4), 453 (1992).